The good point over the SimpleFactory is you can subclass it to implement different ways to create objects.
For simple cases, this abstract class could be just an interface.
This pattern is a "real" Design Pattern because it achieves the Dependency Inversion principle a.k.a the "D" in SOLID principles.
It means the FactoryMethod class depends on abstractions, not concrete classes. This is the real trick compared to SimpleFactory or StaticFactory.
You can also find this code on GitHub
Logger.php
Logger.php
StdoutLogger.php
StdoutLogger.php
FileLogger.php
FileLogger.php
LoggerFactory.php
LoggerFactory.php
StdoutLoggerFactory.php
StdoutLoggerFactory.php
FileLoggerFactory.php
FileLoggerFactory.php
Tests/FactoryMethodTest.php
Tests/FactoryMethodTest.php